The present invention relates to hot melt adhesive and similar coating systems and techniques, being more particularly directed to such systems using thermally sensitive web surfaces in which temperature variations, including those caused by the hot melt depositions, introduce coating variation and degradation.
Previous patents of the common assignee of the present invention, including U.S. Pat. Nos. 3,595,204; 4,020,194; and 4,476,165, describe suitable slot nozzles and applicators for dispensing hot melt adhesive and similar fluid coatings upon moving webs in continuous or intermittent patterns for a myriad of applications ranging from tapes and labels to disposable diaper products and sanitary napkins and the like. There are occasions, however, particularly where very thermally sensitive web materials are involved, as of polyethelene (melting temperature of the order of 140.degree. F.), polypropylene and polyvinyl chloride films or webs and the like, that the hot melt fluid and dispensing nozzle temperatures (order of 300.degree. F. for ethelene vinyl acetate--EVA--or rubber-based hot melts as described in said patents) cause temperature shocks and variations that result in deleterious coating variations and product degradation. It is, accordingly, to the solution of such problems attendant upon the use of hot melt coatings with such thermally sensitive films and the like that the present invention is principally directed.